Creative Commons is starting to work on a version 4.0 in part because:
The treatment of sui generis database rights in the 3.0 licenses
continues to be a show-stopper for many, including governments
in Europe. This fosters an environment in which custom licenses
proliferate, inevitably resulting in silos of
incompatibly-licensed content that cannot be maximally shared
and remixed.
Now is the time to get involved in the CC v4.0 process:
http://creativecommons.org/weblog/entry/30676
-- Sandro